Before the break out of the civil war in 1861, US congress was predominantly divided into two. On one hand legislators from the northern states who were anti-slavery while on the other hand were legislators from the southern states who were pro-slavery. The southerners felt that abolishing slavery would have a negative on their economies while the northern felt that abolishing slavery would help their industries because former slaves would be attracted by paid jobs. To avoid a bloody conflict, several ceasefire meetings were held to quell the rising tensions. The Missouri Compromise of 1820, for instance, helped to create a balance between the number of slave states and free states. This would in effect ensure that southern states had an equal voting power as the northern states in Congress. However, this was not enough.
The tensions between pro-slaves and anti-slaves continued to rise, and the led to the Compromise of the 1850. The compromise saw both sides of the politcal divide agree on the control of the newly acquired states (after the American-Mexican War). However, each side did not get what they bargained for and this allowed dissatisfactions continue to simmer below the surface. This led to the Kansas-Nebraska Act of 1854, which allowed settlers in those states to determine whether they would allow slavery within their borders However, opponents of slavery read the move as an attempt by rich white owners to buy the best lands in Kansas and continue with expansion of slavery. As a result, they read the move as a victory for the pro-slaves. Nevertheless, the differences did not result into an immediate conflict, and the temporary peace continued.
The election of President Lincoln in the 1860 elections was the game changer. President Lincoln was viewed as anti-slave trade and this made southern states uncomfortable. As a consequence, some states filed for secession. The result was a bloody civil war, which government allied-forces won. Since then slavery was abolished.
Miller, F. P., Vandome, A. F., & McBrewster, J. (2010). Missouri Compromise. New York,
NY : Alphascript Publishing. P. 76.
Schultz, K. (2012). HIST. Stamford, CT: Cengage Learning . P. 400.
Waugh, J. C. (2003). On the Brink of Civil War. Lanham, MA : Rowman & Littlefield. P. 98.